The present application relates to a vent valve assembly and particularly to a pressure and vacuum relief assembly for a vehicle fuel tank.
Conventional pressure and/or vacuum relief valve assemblies for vehicle fuel tanks are generally known and are in relatively widespread use. Examples include U.S. Pat. No. 4,498,493 to Harris; U.S. Pat. No. 4,779,755 to Harris; and U.S. Pat. No. 5,794,806 to Harris et al., the disclosures of which are incorporated by reference herein.
It is desirable to provide an assembly that vents a fuel tank when a predetermined pressure or vacuum develops in the tank and that minimizes leakage of fuel vapor.
According to the present application, an apparatus is provided including a valve assembly to relieve pressure and vacuum levels in a fuel tank. The valve assembly comprises a structure providing a valve passageway communicating with the interior of the fuel tank. The passageway provides an axially inwardly facing annular valve seat or edge surrounding an orifice. A vacuum valve member is normally biased to close the orifice. Illustratively, the vacuum valve member provides a frustoconical outer wall facing and extending into the orifice and the outer wall presents a lubricious surface that abuts the valve seat to close the orifice. The vacuum valve member preferably carries a lubricious sealing member which engages the passageway.
In illustrative embodiments, the vacuum valve member includes an intermediate wall that is coupled to the outer wall and faces axially outwardly. The intermediate wall is coupled to an inner frustoconical wall defining a central venting orifice to vent pressure from the fuel tank. The intermediate and inner walls preferably present lubricious surfaces. In illustrative embodiments, the lubricious surfaces are included on the sealing member presented by the outer, intermediate, and inner walls of the vacuum valve member.
The valve assembly further includes a pressure valve member that normally closes the central orifice. The pressure valve member includes an annular valve lip to engage the lubricious surface presented by the intermediate wall and includes an annular rim spaced apart from the lip to engage the lubricious surface presented by the inner wall. Thus, a dual seal is formed to normally close the central venting orifice.
In illustrative embodiments, the vacuum valve member is biased by a first spring so that the surface presented by the outer wall normally engages the edge or valve seat, closing the orifice. The pressure valve is biased by a second spring so that the lip and the rim engage the surfaces presented by the intermediate and inner walls of the vacuum valve member to close the central venting or pressure orifice.
When the pressure in the fuel tank exceeds a predetermined level, the pressure valve member moves axially outwardly. The lip and the rim disengage the intermediate and inner walls of the vacuum valve member or the sealing member carried thereon, opening the central venting orifice. With the central venting orifice opened, fluid flows from the tank through the central venting orifice, relieving pressure in the fuel tank. After the pressure in the fuel tank reaches an acceptable pressure level, the second spring again biases the pressure valve member to close the central venting orifice.
When the vacuum level in the fuel tank exceeds a predetermined level, the vacuum valve member moves axially inwardly. The vacuum valve member disengages the valve seat, opening the orifice. With the orifice opened, fluid flows past the orifice and toward the fuel tank, relieving the vacuum in the fuel tank. After the pressure in the fuel tank reaches an acceptable vacuum level, the first spring again biases the vacuum valve member to close the orifice.
Additional objects, features, and advantages of the present application will become apparent to those of ordinary skill in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the subject matter of this application as presently perceived.